1. Field of the Invention.
The present invention is directed to ladders and methods of making ladders, and in particular, it is directed to a bracket which serves as a guide in making a ladder and which provides additional structural integrity to the ladder once the ladder is made.
2. Description of the Prior Art.
In the construction industry, ladders are often made at the construction sight. The ladders are used for transport between different elevations above ground or entry into and out of trenches below ground. On any given large project, as many as 100 ladders may be built.
One of the reasons for so many ladders being constructed on the job sight is the high cost of factory made step or extension ladders. In addition, due to the many uses of ladders at a construction sight, the ladders often have to be of different lengths. The lengths can vary from two feet to twenty feet. Furthermore, the ladders at a construction sight are subject to a high degree of use or damage and often need to be replaced or repaired.
Recently, OSHA regulations have been written specifying minimum requirements for ladders constructed on construction sights. Previous to the OSHA regulations, ladders were built using 2.times.4's as side rails with 1.times.4 wooden rungs that were nailed to the side rails with two or three nails. These types of ladders are now unacceptable at construction sights due to the OSHA regulations.
Some patents which describe ladder construction include the following:
______________________________________ Inventor U.S. Pat. No. ______________________________________ Flora 285,605 Cole 588,130 Williamson 727,047 Messacar l,475,078 Kramer et al l,595,952 Little 1,775,285 Shuck 2,300,0l8 Hanesse 2,611,l60 Campbell 2,885,l32 Mintz 4,024,929 Hughes 4,060,l50 ______________________________________
The Shuck U.S. Pat. No. 2,300,018 describes a bracket with attaches ladder rungs to vertical members of a ladder. Each rung needs one bracket at each end of the rung to attach the rung to the vertical members, or two brackets per rung.
The Cole U.S. Pat. No. 588,130, the Williamson U.S. Pat. No. 727,047, the Messacar U.S. Pat. No. 1,475,078, the Little U.S. Pat. No. 1,775,285, and the Hanesse U.S. Pat. No. 2,611,160 also describe arrangements in which the end sections of the rungs of the ladders are attached to the side rails by individual brackets.
The Mintz U.S. Pat. No. 4,024,929 describes a portable ladder that is made of a plurality of similar interfitting rail units which are modular in nature to facilitate assembly and disassembly of a ladder of any desired height. A plurality of similar rung units interfit with and interlock upon the rail units at spaced intervals to form a complete ladder construction.
The Campbell U.S. Pat. No. 2,885,132 describes a ladder whose side rails are made of two longitudinal sections having a plurality of channels which when put together encircle rung ends. Layers of glass-reinforced plastic extend for the entire length of the side rail and encircle each rung end.
The Hughes U.S. Pat. No. 4,060,150 describes a ladder kit that includes elongated tubular side rail sections and rectangular frame sections. The frame sections fasten the side rail sections into coplanar pairs and form the rungs of the ladder.
The Flora U.S. Pat. No. 285,605 describes a ladder in which the side rails are made of two longitudinal sections. The rungs of the ladder fit into slots in the side rail sections. The slots encompass end sections of the rungs when the rail sections are joined together to form the side rails.
The Kramer et al U.S. Pat. No. 1,595,952 describes a ladder in which the rungs are attached to the side rails and are further supported by individual brackets disposed diagonally from the side rail to the rung.